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Recent information about alternative vaccination schedules to control (first step before eradication) PRRS in pig farm
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Comparing alternative vaccination schedules to control PRRS
I. Díaz, M. Gimeno, A. Callén, J. Pujols, S. López, C. Charreyre, F. Joisel, E. Mateu & T. Jirásek([email protected])
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EXPERIMENT 1: Development of PRRSV-specific immune responses after repeated PROGRESSIS®
immunizations
IV IV IV
MLVIV IV
MLV
EXPERIMENT 2: Development of PRRSV-specific immune responses after attenuated vaccine (MLV) primo-immunization followed with a MLV or PROGRESSIS® recall vaccination
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IV = Progressis®Ch= Challenge. Strain2749, EU type. ORF5 99% similar to LV
Evaluation of the humoral responses:
• PRRSV-specific total antibodies (ELISA IDEXX)• PRRSV-specific neutralizing antibodies (VNT)
Evaluation of the cell-mediated immune response:
• PRRSV-specific IFN-γ-secreting cells (IFN-γ-SC)
(n=21) Months of age
GROUP 1,5 2,5 3,5 4,5 5,5 6,5 7.5 (+0) +21
A - IV IV - - IV CH END
B IV IV - - IV IV CH END
C - - - - - - CH END
Experiment 1. Development of PRRSV-specific immune responses after repeated
PROGRESSIS® immunizations
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TOTAL ANTIBODIES (ELISA Idexx)
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
-7 PI 0 PI +7 PI +14 PI + 21 PI
S/P
ratio
A B C
Months of age
Group 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5
A IV IV IV Ch END
B IV IV IV IV Ch END
C Pl Pl Pl Ch END
Positive pigs
Day +0 Day +7
Group A 5/7 7/7
Group B 4/7 5/7
Group C 0/7 0/7
Challenge
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Months of age
Group 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5
A IV IV IV Ch END
B IV IV IV IV Ch END
C Pl Pl Pl Ch END
Months of age7.5 (0 dpi) 14 dpi 21 dpi
A1/71
7/7a
3.7 ± 0.57/7
4 ± 0.6a
B3/7
2.3 ± 0.67/7a
3.8 ± 1.57/7
4.6 ± 0.8a
C0/7
-2/7b
4 ± 06/7
3 ± 0.9b
NEUTRALIZING ANTIBODIES (VNT)
PROPORTION OF POSITIVE PIGSMEAN TITRES (log2) ± STAND. DEV.
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∅
PRRSV
∅
PRRSV
ELISPOT IFN-γ
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CELL-MEDIATED IMMUNITY (ELISPOT IFNγ)
PRR
SV-s
peci
fic IF
N-γ
-SC
/ 10
6 PB
MC
Challenge1.5 2.5 3.5 4.5 5.5 6.5 7.5 (+0
PI)+7 PI +14 PI +21 PI
0
25
50
75
100
125
150
175
A B C
a
b
a
a
a
b
a
b
c
a†
b
a‡
Months of age
Group 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5
A IV IV IV Ch END
B IV IV IV IV Ch END
C Pl Pl Pl Ch END
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Development of PRRSV-specific immune responses after repeated PROGRESSIS®
immunizations
IV IV IV
1. Repeated IV immunizations increased cell-mediated immunity and neutralizing antibodies –after the second immunization-.
2. Development of cell-mediated immunity are supposed to be T helper cells and cytotoxic T-cells (Piras et al., 2005). The pattern observed in the present study agreed with the development of memory cells.
3. After the challenge, IV vaccinated pigs showed a significant increase in the neutralizing antibodies production –in proportion of positive pigs and in mean titres-.
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VACCINATION SCHEDULE BALANCE SAFETY/EFICACY
(n=32) Months of age
GROUP 1,5 4,5 5,5 6,5 7,5
A MLV IV - CH END
B MLV MLV - CH END
C MLV IV IV CH END
D - - - CH END
EXPERIMENT 2: Development of PRRSV-specific immune responses after attenuated vaccine
(MLV) primo-immunization followed with a MLV or PROGRESSIS® recall vaccination
IV = Progressis®Ch= Challenge. Strain2749, EU type. ORF5 99% similar to LV
Evaluation of the humoral responses:• PRRSV-specific total antibodies (ELISA IDEXX)• PRRSV-specific neutralizing antibodies (VNT)
Evaluation of the cell-mediated immune response:• PRRSV-specific IFN-γ-secreting cells (IFN-γ-SC)
Virological analysis• Viremia by RT-PCR (+0,+3,+7,+14,+21)
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(n=32) Months of age
GROUP 1,5 4,5 5,5 6,5 7,5
A MLV IV - CH ENDB MLV MLV - CH ENDC MLV IV IV CH ENDD - - - CH END
0
0,4
0,8
1,2
1,6
2
2,4
2,8
3,2
1,5 2,5 3,5 4,5 5,5 6,5 END
S/P
ratio
ABCD
Challenge
TOTAL ANTIBODIES (ELISA Idexx)
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Months of age4,5 5,5 6,5 (0 dpi) 14 dpi
AMLV+IV
1/81 ± 0
2/8ab
2 ± 1.45/8a
2.8 ± 0.88/8a
3.2 ± 0.7ab
BMLV+MLV
0/8-
4/8a
1.5 ± 15/8a
1.6 ± 0.97/8ab
2.1 ± 1.3b
CMLV+IV+IV
3/81 ± 0
5/8a
1.4 ± 0.5 6/8a
2.2 ± 1.68/8a
3.6 ± 1.2a*
DCONTROL
0/8-
0/8b
-0/8b
-4/8b
2.2 ± 0.5b
PROPORTION OF POSITIVE PIGSMEAN TITRES (log2) ± STAND. DEV
(n=32) Months of age
GROUP 1,5 4,5 5,5 6,5 7,5
A MLV IV - CH END
B MLV MLV - CH END
C MLV IV IV CH END
D - - - CH END
NEUTRALIZING ANTIBODIES (VNT)
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(n=32) Months of age
GROUP 1,5 4,5 5,5 6,5 7,5A MLV IV - CH ENDB MLV MLV - CH ENDC MLV IV IV CH ENDD - - - CH END
1,5 2,5 3,5 4,5 5,5 6,5 (+0 PI) +7 PI +14 PI +21 PI0
25
50
75
100
125
150
175
200
A B C
PRR
SV-s
peci
fic IF
N-γ
-SC
/ 10
6 PB
MC
a
a
b
c
a
ab
b
c
a†
b
ab†
b
a
ab
b
aa
b
b
b
MLVPrimo-immunization
Re-vaccination
Challenge
CELL-MEDIATED IMMUNITY (ELISPOT IFNγ)
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(n=32) Months of age
GROUP 1,5 4,5 5,5 6,5 7,5
A MLV IV - CH END
B MLV MLV - CH END
C MLV IV IV CH END
D - - - CH END
A 0 3 79 - - +12 - - -15 - - +18 - - -21 - - -24 - + -27 - - -30 - - -
VIREMIA by RT-PCR
B 0 3 7 10 - - -13 - - -16 - - +19 - - -22 - - -25 - - -28 - - -31 - - -
C 0 3 7 11 - - -14 - - -17 - - -20 - - -23 - + -26 - + -29 - - -32 - - -
D 0 3 7 1 - + -2 - + -3 - + -4 - + -5 - + -6 - + +7 - + -8 - + -
No significant differences among
vaccinated groups
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Development of PRRSV-specific immune responses after attenuated
vaccine (MLV) primo-immunization followed with a MLV or
PROGRESSIS® recall vaccination
After a MLV primo-immunization:
1. IV re-vaccination induced a significant increase in the development of cell-mediated immunity (anamnestic response).
2. After the challenge, MLV+IV+IV group developed the highest PRRSV-specific immune responses (cell-mediated immunity and neutralizing antibodies).
3. All the vaccination schedules reached similar levels of protection.
MLV
IV IV
MLV
VACCINATION SCHEDULE BALANCE SAFETY/EFICACY
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